New cylinder heads or what?

[JohnL]

Very long tale of woe with my V6 Omega ... to cut a long story short, where I've ended up is that some of the threads for the bolts holding the inlet manifold to the cylinder heads have become stripped. So I can't tighten the bolts to the correct torque.

So ... is there a way of fixing this - should it be possible to over-drill and use bigger bolts? Or is there some stuff I could fill the holes with and tap a new thread into? It needs to take 20Nm of torque. Maybe longer bolts could grab some thread further down?

I'll be absolutely gutted if this means new cylinder heads

[HarryW]

John haven't looked whether they are bolt holes or studs in the head, but either way not head reason to replace the heads. If they're studs they can be replaced quiet easily or if they are bolt holes and the thread in the heads has gone then these should be able to be helicoiled(being ally heads). If beyond simple (your and mine) diy then most garages shouldn't charge the earth for this type of work. The expense may come though, if the heads have to come off for the work though.

Harry

[deltaf]

Helicoil /recoils will fix it, permanently.
Most decnt engine shops/reconditioners could do this for you.

[JohnL]

Thanks guys. They're definitely bolt holes, I've just reassembled the inlet manifold for the second time (the garage having done it once as well). I suspected some holes were stripped the first time, then I convinced myself they were OK and it was just crud in the threads ...

So I took it apart again (because it was running unevenly) and fitted new gaskets (£42 for 12 rubber bands ...) and torqued the bolts up properly, and some of them wouldn't tighten - I took one out again and if brought a fair bit of thread with it .

I'll never know if it was the garage or me that stripped them in the first place. The more I think though, the more I suspect it was me ... anyway if it still doesn't all seal properly I'll pay someone else to fix it with new coils, I'm fed up of the sight of that friggin' engine for now



>> Edited by JohnL on Monday 19th May 23:49

[Captain Muppet]

Helicoils can be fitted yourself, it's not that tricky. I did loads on ally production line machinery in a previous job. If there's room for the inlet manifold there should be room for the tap for the helicoil, so you won't need to take the head off.